Added: support for selector transformation (#29)

([#29](#29) - @uniquegestaltung)

Author: martinkutter

README.md

@@ -134,6 +134,25 @@ var out = postcss()
   .css
 ```
 
+#### `selectors` (default: `false`)
+
+Allows calc() usage as part of selectors.
+
+```js
+var out = postcss()
+  .use(calc({selectors: true}))
+  .process(css)
+  .css
+```
+
+Example:
+
+```css
+div[data-size="calc(3*3)"] {
+  width: 100px;
+}
+```
+
 ---
 
 ## Contributing

index.js

@@ -16,6 +16,7 @@ module.exports = postcss.plugin("postcss-calc", function(options) {
   var preserve = options.preserve
   var warnWhenCannotResolve = options.warnWhenCannotResolve
   var mediaQueries = options.mediaQueries
+  var selectors = options.selectors
 
   return function(style, result) {
     function transformValue(node, property) {
@@ -53,6 +54,9 @@ module.exports = postcss.plugin("postcss-calc", function(options) {
       else if (rule.type === "decl") {
         return transformValue(rule, "value")
       }
+      else if (selectors && rule.type === "rule") {
+        return transformValue(rule, "selector")
+      }
     })
   }
 })

test/fixtures/selector.css

@@ -0,0 +1 @@
+div[data-size="calc(3 * 3)"] {}

test/fixtures/selector.expected.css

@@ -0,0 +1 @@
+div[data-size="9"] {}

test/index.js

@@ -49,6 +49,13 @@ test("calc", function(t) {
     "should resolve media queries"
   )
 
+  compareFixtures(
+    t,
+    "selector",
+    {selectors: true},
+    "should resolve selectors"
+  )
+
   compareFixtures(
     t,
     "precision",